In addition to active antiperspirant substances, water-free, antiperspirant suspensions sprayable with a propellant generally contain at least one cosmetic oil as carrier for the particulate active sweat-reducing substance. The suspensions are packaged in a pressure-resistant container, usually a can of tin plate or aluminum, which is lacquered on the inside, together with a liquefied hydrocarbon, such as n-butane, isobutane and/or propane, as propellant. Before using the spray valve, during which propellant and a proportion of the suspension are released, the container must first be shaken sufficiently to mix in the active antiperspirant substance which has settled out. To ensure that the suspended active antiperspirant substance does not immediately settle out again, commercial suspensions contain a suspending agent, for example hydrophobically modified hectorites, as available, for example, with the trade name Bentone Gel from Rheox and Elementis Specialties, or also hydrophilically and/or hydrophobically modified silicas.
In commercial sprays, the active antiperspirant substance suspended in the water-free carrier is covered with an oil layer. During and after application onto the skin, this oil layer is favorable for the spray pattern, in other words the active substance is not excessively atomized, but instead arrives in targeted manner on the skin; the oil layer moreover ensures a certain level of adhesion of the powdered active antiperspirant substance to the skin. However, this oil layer delays the release of the active antiperspirant substance in the effective water-soluble form.
In the prior art, water-containing antiperspirant creams with a water content of 43.9 wt. % are known from U.S. Pat. No. 5,118,497 and U.S. Pat. No. 5,017,360, which are emulsified with the aid of the commercial product Elfacos ST-37, an alkyl-modified polyether with the INCI name PEG-22/Dodecyl Glycol Copolymer, which has an HLB value of 2.4.
U.S. Pat. No. 6,613,338, and in particular WO 98/17238 A1, disclose sticks, in particular antiperspirant sticks, in the form of solid water-in-oil emulsions with a water content of 30-85 wt. %, which are emulsified with the aid of an alkyl-modified polyether of the general formula ACTIVATOR-(I) with the INCI name Methoxy PEG-22/Dodecyl Glycol Copolymer. This prior art gives the person skilled in the art no indication that alkyl-modified polyethers of the general formula ACTIVATOR-(I) might improve the release of the active antiperspirant substance from a water-free composition.
WO 2009/083547 A2 and WO 2009/083807 A2 teach that certain organosiloxane-oxyalkylene copolymers can improve the release of the active antiperspirant substance from a water-free composition. As a disadvantage of these substances, however, it has been shown that under certain circumstances, in particular when the cosmetic carrier contains little or no silicone oil, they are difficult to incorporate and to mix in homogeneously.
Desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.